1. Field of the Invention
The present invention relates to a paper treating unit such as a paper exhausting unit connected at the latter stage of an image forming apparatus such as a copier or a laser beam printer.
2. Background Art
The paper exhausting unit is provided at the latter stage of the image forming apparatus to enable the printed paper from the image forming apparatus to be loaded in order. This paper exhausting unit is required to align the paper in order in a paper proceeding direction and a perpendicular direction (paper width direction) to the paper proceeding direction in consideration of the post-processing such as bookbinding.
In JP-A-11-138966, there was disclosed a paper receiving unit for aligning the printed paper. This paper receiving unit comprises a pair of width guide plates arranged in parallel to the paper proceeding direction on a paper receiving tray, and a stop guide plate against which the front edge of the paper abuts. The width guide plates and the stop guide plate can be slid back and forth in the paper width direction and the paper proceeding direction, respectively. Each guide plate is moved from an open position to a closed position to align the paper on the paper receiving tray at a predetermined position, every time one paper is placed on the paper receiving tray. Each guide plate presses the paper to the predetermined position and then returns to the open position.